1. Field of the Invention
The invention relates to a scroll-type compressor improved to smooth the orbiting movement of a movable scroll.
2. Description of the Related Art
A scroll-type compressor generally comprises movable and stationary scrolls. The movable scroll includes a movable end wall and a movable spiral member which are connected to each other. The stationary scroll includes a stationary end wall and a stationary spiral member which are connected to each other. The movable and stationary scrolls engage with each other to define compression chambers therebetween. The movable scroll is held by front and rear housings to move along an orbiting path. The orbiting movement of the movable scroll shifts the compression chambers from the periphery to the center of the movable and stationary scrolls to reduce the volume of the respective compression chambers.
In some scroll-type compressors a slider plate, for smoothing the orbiting movement of the movable scroll, is provided between the front housing and the movable end wall of the movable scroll.
A scroll-type compressor described in Japanese Unexamined Patent Publication (Kokai) No. 6-121113 has fixed and movable slider plates which are provided between an inner end face of a front housing and a movable end wall of a movable scroll through an arrangement for preventing the movable scroll from rotating about its axis. The arrangement for preventing the movable scroll from rotating about its axis comprises a fixed ring with one or more recesses disposed along the periphery thereof, a movable ring with one or more recesses disposed along the periphery thereof, and ball elements inserted into each of the recesses of the fixed and movable rings. A fixed race is provided between the inner end face of the front housing and the fixed ring, which is secured to the front housing by means of a spring pin and caulking along the fixed ring. A movable race is provided between the movable end wall and the movable ring, which is fixed to the movable end wall by means of spring pins and caulking along the movable ring.
The method of providing a slider plate described in the publication, however, inherently involves a problem that manufacturing cost is increased since the slider plates are secured by caulking, which increases the stages of the manufacturing process of a scroll-type compressor. In addition to this, the slider plate secured by means of caulking cannot be replaced at the end of its life because it is connected to the front housing by caulking, which results in the replacement of all of the associated components.
On the other hand, connection by only the spring pins is insufficient to secure the slider plates since the spring pins are elastic members, and they may easily become loose against the associated elements such as the slider plates or the inner end face of the front housing, due to the compression load and vibration, etc., during operation of the compressor. Such loosening between the spring pins and the slider plates may result in the noise and friction which often appear in a compressor with a slider plate which is not secured so that the plate rotates with a movable scroll. Further, when the spring pins are loosened to fall off the front housing, they obstruct the operation of the compressor.